Since divestiture it has been possible for telephone subscribers to own their own equipment and to connect such equipment to the incoming telephone lines of the operating company. This has created the necessity of providing a demarcation point to facilitate determination of whether a fault exists on the incoming telephone line or the subscriber premises line. Typically this is currently provided by telephone network apparatus mounted at the subscriber premises which includes a terminal box having both telephone company and subscriber compartments for mounting the respective telephone company and subscriber terminals and other equipment. Typically separate doors or covers close the compartments and provide access to the telephone company and subscriber respectively.
A telephone jack is normally provided for connection to the incoming telephone line and a telephone plug for connection to the subscriber premises line. Upon the telephone jack and plug being connected to such lines and the plug being plugged into the jack a telephone connected to the subscriber premises line is rendered operable. Should the telephone become inoperable the telephone plug is unplugged from the telephone jack and provides a demarcation point to permit the plug of an operating telephone to be plugged into the jack to facilitate determination of whether a fault exists on the incoming telephone line or the subscriber premises line. Representative of such prior art telephone network interface apparatus or devices are those described in U.S. Pat. Nos. 4,488,088 issued Dec. 11, 1984; 4,500 58 issued Feb. 19, 1985 and 4,647,725 issued Mar. 3, 1987.
Generally devices of this type are most suited to subscriber premises having a relatively small number of incoming telephone lines interconnected to a matching number of subscriber premises lines. However the telephone network system serves a large variety of customers including office buildings, condos, apartments and the like wherein it is necessary to terminate 25, 50 or perhaps hundreds of incoming telephone lines for interconnection with an equally large number of subscriber premises lines.
Generally speaking existing interface devices are designed to accommodate 25 or 50 or less lines. Where additional lines are to be served additional interfaces are required.
Exemplary illustrations of currently used or proposed devices are provided in the following:
U.S. Pat. No. 4,658,422, issued Apr. 14, 1987, shows a terminal box having a 2-part outer cover connected by a hinge. The box with the cover removed comprises a right chassis in the right compartment and a left chassis in the left compartment. The two chassis are hinged together. The left chassis may be raised to gain access to the interior of the underlying compartment as seen in FIG. 4. A terminal block is mounted on the chassis in the subscriber's compartment of the box and this is used for connecting the subscriber's telephones. The terminal block provides connections for up to 25 telephones. A protector block is mounted on chassis in the telephone company compartment. The terminal block in the subscriber compartment is factory wired to contacts on the under side of the protector block as shown in FIG. 8. The back of the protector block may be encapsulated. The telephone cables enter the telephone company compartment through a bushing beneath the protector block and are spliced to a connector attached to the under side of the protector block. No provision is made for an electronics field. The terminal boxes are provided as completed units and expansion is accomplished by adding additional stacked boxes.
U.S. Pat. Nos. 4,979,209 and 4,945,559, issued Dec. 18, 1990, and Jul. 31, 1990, show a network interface device which includes a base, a telephone company cover and a subscriber cover. The telephone company compartment has terminals for connecting to incoming telephone company lines or wiring and includes protector devices. The protector devices are not of the modular plug-in variety. The subscriber compartment contains terminals for connection to subscriber premise lines or wiring. The terminals include pairs of terminals mounted on a plurality of replaceable individual subscriber line modules shown in FIGS. 7-10. Each module is box-like and hollow to provide an internal space (FIG. 8) for receiving a telephone circuit comprising the so-called "electronics". These electronics are thus provided on the subscriber side and may be changed only by changing the entire subscriber line module. The modularity and removability of the individual subscriber line modules is a basic feature of this device. The interface shown accommodates from 1-6 subscriber lines.
U.S. Pat. No. 4,949,376, issued Aug. 14, 1990, shows a telephone interface terminal having separate telephone company and subscriber access. Several different cover hinging arrangements are shown. The specific embodiment is adapted to handle five subscriber lines and the subscriber line connections are provided in the form of modules adapted to be used with terminal blocks referred to in the art as 66 blocks. The modules are provided with space for housing electronics circuits.
U.S. Pat. No. 4,919,544, issued Apr. 24, 1990, shows a retrofit apparatus for mounting on a conventional 66 block to provide a demarcation point. The retrofit modules are provided with space for mounting electronics circuits. This device deals with the problem of providing a demarcation point for 25, 50, etc. multi-line terminal blocks previously installed. Such multi-line terminals found at office buildings, apartments, etc., present different problems from the relatively limited number of lines handled by the devices described in the prior patents discussed above.
U.S. Pat. No. 4,752,249, issued Jun. 21, 1988, shows a telephone distribution frame connector which includes a module field, a test field and an equipment field. A module field block is provided which mounts on the outer side thereof a plurality of over voltage or surge protector modules. A field test block and equipment field block are mounted at right angles to the module block.
U.S. Pat. No. 4,605,275, issued Aug. 12, 1986, shows a modular encapsulated cross-connect terminal unit for mounting in a cross-connect terminal.
U.S. Pat. No. 3,936,133, issued Feb. 3, 1976, shows a connector block for mounting plug-in type protector assemblies.
U.S. Pat. No. 4,712,232, issued Dec. 8, 1987, shows an 89 mounting bracket and a multiple telephone jack slide assembly. Each telephone jack is coupled by color coded wires to rows of terminals provided by a punch down terminal board. Similarly each of the mating telephone plugs is coupled by color coded wires to associated rows of terminal provided by a punch down terminal board.
U.S. Pat. No. 4,749,359, issued Jun. 7, 1988, shows a telephone network interface device having separate telephone company and subscriber compartments and containing individual access doors.
In addition to the foregoing some interface arrangements in use today have provisions to install electronic devices such as Radio Frequency Interference (RFI) filters within the cabinet on binding posts or a punch-down block. In this configuration the electronics termination point is located between the protector field and the subscriber wire termination field. This has the practical effect of creating a miniature cross-connection fixture, which results in record keeping problems for both the assignment and repair bureaus. When several electronic devices are terminated on the field provided for this purpose the terminal fixture tends to become what is known colloquially as a "rat's nest".
Some interfaces are made with Network Interface Devices (NIDs) such as RJ11s hardwired into the cabinet. These cabinets are used in applications where limited space is provided for telephone company use by the subscribers. The NIDs in these cabinets are equipped with lugs or binding posts known as an entrance bridge. The entrance bridge, typically a so-called 66 block, is where the subscribers terminate their service wires. When the NID is a component of the terminal provisions are made in the cabinet to deny the subscriber access to all network component areas while providing the subscriber ready access to the NID itself in order to terminate and test their customer premises equipment. Terminals in this configuration are relatively expensive. Also the NID component itself is susceptible to damage since this unit is handled by the subscriber rather than a trained telephone technician. The NID is an integral component when included in the available terminal configuration so that when the NIDs are damaged the entire terminal may have to be replaced at substantial cost.
The disadvantages of existing building entrance terminals (BETs) include the following:
Existing BETs utilized for interior, exterior or pedestal mount applications differ greatly in design, size and components.
The largest known available outdoor unit handles 50 lines.
When electronics fields are included in existing BETs, the BET becomes a cross-box which introduces severe records problems in the assignment and repair service bureaus.
When pig-tailed type electronics are placed in the provided fields in existing BETs a wiring rat's nest is created.
Existing BET product as currently designed cannot be expanded with an increase in service requirements. If a 25 line fixture is installed and additional service is required a second fixture is necessitated.
Components in existing BET products cannot be easily replaced when damage occurs. The NIDs are usually part of the cabinet.
Existing BETs have a substantial initial cost and since the components cannot be readily repaired or replaced they also have a potentially high maintenance cost.